Description

The MD4 functions implement the MD4 message-digest algorithm. The algorithm takes as
input a message of arbitrary length and produces a “fingerprint” or “message
digest” as output. The MD4 message-digest algorithm is intended for digital signature applications
in which large files are “compressed” in a secure manner before being
encrypted with a private (secret) key under a public-key cryptosystem such as
RSA.

MD4Init(), MD4Update(), MD4Final()

The MD4Init(), MD4Update(), and MD4Final() functions allow an MD4 digest to be
computed over multiple message blocks. Between blocks, the state of the MD4
computation is held in an MD4 context structure allocated by the caller. A
complete digest computation consists of calls to MD4 functions in the following
order: one call to MD4Init(), one or more calls to MD4Update(), and
one call to MD4Final().

The MD4Init() function initializes the MD4 context structure pointed to by context.

The MD4Update() function computes a partial MD4 digest on the inlen-byte message
block pointed to by input, and updates the MD4 context structure pointed
to by context accordingly.

The MD4Final() function generates the final MD4 digest, using the MD4 context
structure pointed to by context. The MD4 digest is written to output.
After a call to MD4Final(), the state of the context structure is undefined.
It must be reinitialized with MD4Init() before it can be used again.

Return Values

These functions do not return a value.

Security

The MD4 digest algorithm is not currently considered cryptographically secure. It is
included in libmd(3LIB) for use by legacy protocols and systems only. It should
not be used by new systems or protocols.

Examples

Example 1 Authenticate a message found in multiple buffers

The following is a sample function that must authenticate a message that
is found in multiple buffers. The calling function provides an authentication buffer
that will contain the result of the MD4 digest.